As a rare earth metal oxide, ceria has a unique redox chemical property. Due to the presence of cerium in two oxidation states (Ce3+ and Ce4+), ceria has a very wide range of applications in the fields of catalysts, secondary batteries (e.g., lithium ion batteries, lithium sulfur batteries, etc.), and supercapacitors.
The performance of ceria, whether regarded as a catalytic material or an electrode material, depends critically on its BET (Brunauer, Emmett, and Teller) surface area. Increasing the BET surface area of ceria can greatly improve its performance in catalysis and its performance as an energy storage electrode material. Therefore, it is a very effective method to increase the BET surface area by nanocrystallization of ceria or by making ceria into a hollow structure, and so on. However, when ceria is used as the electrode material, in the case of charge and discharge of the electrode, the ceria has a volume expansion due to a change in valence state of cerium ions, such that the electrode is easily collapsed, resulting in a sharp decrease in performance.
In the application process, the performance of ceria cannot make a better achievement due to its poor conductivity. For example, when ceria is used as the electrode material of the supercapacitor, its specific capacity, rate performance, and cycle stability are low due to its low conductivity. Therefore, in order to improve the performance and application of ceria, it is still necessary to design a novel structure to overcome the drawbacks existing in the current application process.